1. Field of the Invention
The present invention relates to a display device, and more particularly to a technique which is effectively applicable to a liquid crystal display device (liquid crystal display module) used in a portable electronic device such as a mobile phone terminal.
2. Description of Related Art
Conventionally, as a display of a portable electronic device such as a mobile phone terminal or a PDA (Personal Digital Assistant), for example, a thin display device such as a liquid crystal display device is used. Here, the display device used in the portable electronic device is also referred to as a display module.
The liquid crystal display device is a display device which includes a liquid crystal display panel sandwiching a liquid crystal material between a pair of substrates. Here, one of the pair of substrates is generally referred to as a TFT substrate and such a TFT substrate is constituted by forming TFT (Thin Film Transistor) elements, pixel electrodes and the like on a glass substrate, for example. Further, another of the pair of substrates is generally referred to as a counter substrate and such a counter substrate is constituted by forming color filters and the like on a glass substrate, for example. Here, when the liquid crystal display panel adopts a vertical electric field method as a method for driving the liquid crystal material, common electrodes which face the pixel electrodes in an opposed manner are formed on the counter substrate side. On the other hand, when the liquid crystal display panel adopts a lateral electric field method as the method for driving the liquid crystal material, the common electrodes are formed on the TFT substrate side.
Recently, efforts for making a body of the portable electronic device thin have been made and along with such efforts, efforts for making the liquid crystal display device which is used in the portable electronic device thin have been also made. As a method of making the liquid crystal display device thin, for example, a method which makes the liquid crystal display panel thin has been known.
As the method which makes the liquid crystal display panel thin, for example, a method which makes the glass substrate used as the TFT substrate or the counter substrate thin by grinding has been known.
Further, as the method which makes the liquid crystal display panel thin, for example, a method which uses a plastic substrate in place of the glass substrate as either one of the TFT substrate or the counter substrate has been also known (see JP-A-8-006039, for example).